template<typename T, typename X, typename Y>
void myFunc(T<X,Y> map, X x, Y y) {
    map[x] += y;
}

template <template <typename, typename> class M, typename K, typename V>
void Foo(M<K, V> & container)
{
  // ...
};

template <template <typename, typename, typename...> class M, typename K, typename V, typename ...Args>
void Foo(M<K, V, Args...> & container)
{
  // ...
};

template <typename Container> void FooImpl(Container &);

template <template <typename, typename> class M,
          typename K, typename V>
void Foo(M<K,V> & c) { FooImpl(c); }

template <template <typename, typename, typename> class M,
          typename K, typename V, typename A1>
void Foo(M<K,V,A1> & c) { FooImpl(c); }

template <template <typename, typename, typename, typename> class M,
          typename K, typename V, typename A1, typename A2>
void Foo(M<K,V,A1,A2> & c) { FooImpl(c); }

// etc.

template<typename T, typename X, typename Y>
void myFunc(T map, X x, Y y) {
    map[x] += y;
}

template<typename T>
void myFunc(T map, typename T::key_type x, typename T::mapped_type y) {

template<typename T, typename X, typename Y>
void myFunc(T map, X x, Y y) {
    map[x] += y;
}

// ...

map<int, int> myMap;
myFunc(myMap, 5, 7);